The invention relates to a seal for an exhaust aftertreatment device in an internal combustion engine.
In the case of dosing devices for DENOX systems, for example, use is made of a dosing module which contains a dosing valve for injecting the reducing agent into the exhaust zone and which ensures the attachment of hydraulic components and the cooling of the unit. For connection to the exhaust zone, the dosing module has a flange, which is flanged to a mating flange on the exhaust pipe. Because of manufacturing tolerances and roughness of the mating flange on the exhaust pipe, there is the risk of leaks, especially at the transition from the interior of the exhaust pipe to the exterior. In DENOX systems, the reducing agent AdBlue®, which is distinguished by very high creep properties, is generally dosed in. If the reducing agent escapes, white crystals form on the outside of the dosing device. Ammonia which escapes during this process is toxic. A particular challenge with such an exhaust aftertreatment device is therefore the sealing of the interior of the exhaust system with respect to the surroundings, not only because of the exhaust gases but especially because of the reducing agent.
In order to prevent the exhaust gases and the reducing agent from escaping, DE 10 2006 061 730 A1 discloses the practice of fitting a seal between the exhaust pipe and the dosing device, said seal comprising a sealing element which rests flat on a flange of the dosing module and on a mating flange of the exhaust pipe. The dosing module is secured by means of a V clamp, which nonpositively connects a flange of the exhaust pipe to a retaining structure for the dosing module.
U.S. Pat. No. 6,814,303 B2 discloses a fluid-cooled mount for an injector, by means of which an aqueous urea solution is introduced into an exhaust section. In this case, the injector body is seated on oblique internal walls of a mounting piece, wherein a seal, which can be designed as an O-ring or as a flat gasket, is provided at the point of contact.